Oil burner control systems



Spt- 27 1956 J. R. GAGE ETAL OIL BURNER CONTROL SYSTEMS 5 Sheets-511%?l l Filed Nov. 27, 1963 mSNuQ Rww QMNN% xLI. XTM

Sept. 27, 1966 Filed Nov. 27, 1963 J. R. GAGE ETAL OIL BURNER CONTROL SYSTEMS 5 Sheets-Shea?. 2

FIG. 2

fx I //8 l Sept. 27, 1966 J. R. GAGE ETAL OIL BURNER CONTROL SYSTEMS.

5 Sheets-Sheet 5 Filed Nov. 27, 1963 BY m, mfr

United States Patent Office 3,275,058 Patented Sept. 27, 1966 3,275,058 OIL BURNER CONTROL SYSTEMS Jack R. Gage and Bernard Diamond, Hicksville, N.Y., assignors to D-G Controls, Inc., Hicksville, N.Y., a corporation of New York Filed Nov. 27, 1963, Ser. No. 326,501 13 Claims. (Cl. 158-28) This invention relates to oil burner control systems and more particularly to primary control systems which sense the presence of combustion in an Voil-tired burner and serve to shut down the burner in the event that the burner should malfunction for any reason.

Among the many advantages ofoil burner control sys-V tems embodying the present invention are those resulting from the fact that they are safety systems having fail-safe characteristics, namely that they shut down the oil burner in the event of a malfunction either in the burner or in the control system itself. Moreover, these control systems may include a warning device as an integral part of the system so as to provide a warning signal whenever a burner malfunction does occur. In addition, these control systems enable the emergency shut-off switch, which is located remotely from the burner to be used as reset control means for resetting the system. This emergency switch is often a toggle-type switch and is usually located at a convenient point in the living quarters such as in the kitchen or in a hallway -near the top of the cellar stairs, and the present invention enables the control system to be reset by the homeowner from this convenient point by turning this switch oi for a brief period of t-ime.` Also,

control systems embodying the present invention are extremely reliable in operation and are easy to service whenever the occasion arises.

The control .systems embodying the present invention are adapted to lock themselves electrically into the condition wherein the burner is de-energized after a malfunction has occurred, and when the homeowner interrupts the circuit at a remote point the system resets itself into condition to attempt to initiate proper operation of the burner.

The domestic oil supply industry in most areas of this country undertakes the responsibility of servicing domestic oil burner installations and of maintaining them in proper operation condition. For many years this industry has been plagued with the fact that most service calls are received early in the morning or in the evening hours. The reason for this is that in most conventional systems there is no warning provided t-o the homeowner when the oil burner malfunctions. Consequently, whenever the burner shuts down during the night the homeowner usually does not know about it until he arises in the morning to nd that the house is unpleasantly chilly or that there is no hot water for the morning shower. In many homes having oil burners for space heating the domestic hot water supply is also heated by this same Iburner. During the daylight hours when the outside temperature is usually higher than at night the house often will maintain a suiciently comfortable temperature so that a malfunction of the oil burner is not noticed until suppertime or after supper when the hot water is required in the kitchen or for bathing. Thus, the service calls tend to occur most often in the early morning hours or evening hours. This places a severe burden upon'the service personnel and causes delays in response to some of the service calls, Yas Well as raising the costs of oil service.

Moreover, in conventional domestic oil burner installations the reset button actuates a mechanical lock-out release and is located on the stack switch unit itself which is on the exhaust duct to one side of or behind the top of the furnace. In order to reset the oil burner the user must move around the furnace and find this button to actuate it.

This is often awkard or diicult, and in many cases the exhaust duct is sooty so that the homeowner hesitates to seek the reset button. In situations where the oil supply service operator is fortunate enough to be called by some- -one who is familiar with oil burner furnaces, the service operator may suggest that he will wait by the telephone while the user goes to the furnace to try to locate and actuate the reset button; so that if the burner does not begin operation again, the user will have saved the time of wating for service and the service operator will have avoided an unnecessary trip. But in many instances the user is unfamiliar with the equipment or yh'esitates to probe about the equipment, in which case the service operator must arrange for a service trip.

In oil burner control systems embodying the present invention the reset button is enabled to be located in the kitchen .or in a hallway or some other convenient point remote from the oil burner itself. Thus, advantageously, the user of the equ-ipment can actuate this reset switch Whenever he nds that the oil burner has malfunctioned. The warning signal prompts him to `actuate this reset switch immediately after the burner .has malfunctioned. If the burner resets and starts operating, then the user is saved the trouble of making a service call and lavoids the inconvenience of a cold house or cold water. If the burner does not begin proper operation 'then the service call is likely to be made at once, thus i-n the aggregate avoiding the tendency for service calls to occur during the morning or evening time periods discussed labove. Also, many unnecessary service calls are thus avoided because those users who are hesitant yto probe around the oil burner equipment will not hesitate to follow a suggestion to press a button which is conveniently at hand.

Following interruption of electrical power, for example after a severe storm, many conventional stack switch un-its which are in use today must be manually reset when the electrical power has -been resumed. This requirement often involves hundreds of service calls for oil supply companies :and considerable delay for customers. Advantageously, with the systems embodying the present invention they automatically reset themselves whenever there is an interruption of electrical power so that the burner resumes its normal operation as soon as the electrical power is restored, thus avoiding any trouble and delay for the user.

It is lamong the objects of the present invention to provide more convenient and safer oil burner stack switch control systems.

- It is among the further objects of the present invention to provide oil burner stack switch control systems which are less complex than many in use today and which are easier to service and more reliable in operation.

In this specification and in the accompanying drawings vare described and shown fuel burner control systems embodying the invention, and it is to be understoodthat this disclosure is not intended to be exhaustive nor limiting of the invention, but is set forth for purposes of illustration in order that others skilled in the art may fully understand the invention and the ymanner of its application in practical use,

The various objects, aspects, and advantages of the present invention will be in part pointed out and in part apparent Ifrom the following description of illustrative embodiments of this invention when considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is a schematic cir-cuit diagram of a fuel burner control system embodying the present invention;

FIG. 1A illustrates remotely located `warning signal devices which may be connected in the system of FIG l;

FIGURE 2 is a schematic diagram of an alternative embodiment of the system of FIGURE l;

FIGURE 3 is a schematic circuit diagram of a modified embodiment of the present invention; and

FIGURE 4 is a partial schematic diagram of a modified embodiment of the present invention. The circuit of FIGURE 4 is identical to the circuit of FIGURES, except that the connection 39 is shown in solid lines with the connection 39 being omitted from FIGURE 4.

In the system of FIGURE 1 is shown a domestic heating fuel burner and an electrical control system 11 including a combustion sensor 12 or heat probe for sensing the presence of energy of combustion in the burner, a thermal time-delay switch 14, a magnetic relay 16, which has its contacts in circuit in series with the fuel burner-circuit, `a buzzer Warning device 18, a main power switch 20 which may serve aS the reset switch, and a uidsensing thermostat 22 which may be responsive to the temperature of the tluid being circulated to the living space which is being heated. Advantageously, thecon-Y trol system 11 is shown asincludinga remote rese'tcon- Y trol switch 24, andV additional elements A which'may also be included in this control system are,y remotewarning devices, for example such as an audible 'signal device 26 and I'a visible signal device 28. Y

The control system 11 isenergizedfrom a suitable electrical source, for example shown as alternating current power lines 29 and 30 for `supplying 1Z0-volt A.C. at

60 cycles. In such A.C. home distribution circuits it is customary to ground one of the lines, and the line 30 is shown as being grounded. It is preferable to have the main power switch 20` connected to the hot line 29, with a fuse 31 in series with this switch. Beyond the fuse 31 is a connection point`33 with an electric wire -34 extending to a remotely located switch 24. This'switch 24 may be the emergency burner shut-off switch which is in existencel in many homes, vor it may 'be aV switch which is especially Vinstalled :to serve the resetpurposes as described further below. In any event, the present invention enables the burner control system to be reset from a convenientswitch remotely located, which isoperated to reset the control system -followingmalfunctioning of the burner. An electric line 35 extends from the other side of the reset switch 24 to a connection point 37l which is connected to the one side of the fluid-sensing thermostat 22. The hot line terminal 32 of the control system 11 is connected to the other side of the thermostat ance to the user.

22,. and from this line terminal 32 a supply line 36 extends to the heat sensor 12 which includes a thermostat element 37, for example, such as a bimetallic element of helical construction, and a pair of normally open contacts 38 which become closed in response to heating of the sensor 12. In this system the-combustion energy sensor 12 is illustratively shown as located in a duct 37A Which serves to carry away the hot gases., products of cornbustion, from the burner 16. It will be understood, however, that this sensor 12 may 'be located at any suitable point in relation to the burner 10 so as to respond to the presence of energy resulting fromfcombustion, such as heat energy or light energy resulting therefrom. The contacts 38 are connected -by a lead 39 so that the contacts 38 are in circuit in shunt relationshipto a heating element 43 kof the thermal time-delay switch 14.

The thermal time-delay switch 144 is a ,snap-acting single-pole double-throw switch includingV a` pair of'` normally closed contacts 40 and a pair ofnormally openv contacts 41. A "bimetallic snap-acting armature element 4 2 is inheat exchange relation with a resistance heater 43 which is connected in seriesfwith the movable contacts closed while the contacts 40 are opened. The reason for using a snap-acting switch is to avoid any open-circuit hesitation between the opening of contacts 40 and the closed.Y p l' .Y

The normally .openV contacts 41 areconnected zbycirso that a make-before-break switch can be used in lieuk p of the snap-acting switch as shown. In this example the Iswitchr14 is housed within an air-tight envelope 45 and is of a type such as can beV obtained commercially from Electronic Fittings Corporation underthe modeldesignation 26.5-60-G.

From the normally closed contacts 40 a connection is made through a solenoid winding 46 of the lmagnetic relay 16 to a terminal 48. which is the ground terminal of the control system 11, and this ground terminal is adapted to be connected to the opposite side of the'electrical Isource from the line terminal 32. open lcontacts 49 of the relay.16are in series -with a terminal 50 of the control system, which is called 'theY burnerl terminal of the control system 11 land'servcs.,r

t'o energize the burncrldwhen these contacts .49Qare cuit means r51,'to `the groundY power terminal p48.' The. circuitmeans 51 provide anelectrical connection-be-` tween the contacts 41 and the .power terminalSand mlay include-the Warning device' 18 as shown tin FIGURE l. Alternatively, the warning device 18 maybe included in association with the magnetic relay 16, as shown `in FIG- URE 2, in which event 'the circuit means 51 may not include a warning device. The magnetic relay 16 Ias shown in FIGUREl usually does include aset of normally closed contacts 62 which may be usedV to control a remote warningv device as indicated'bythe :connection karrows Yx, x, to terminals S5 and 48.

In operation of thisburner system there are a variety of sequences of events which might arise kto cause a malfunction,'and these various sequences are reviewed herel ,n

provides fail-safe assur.- i

inatter to showahow -this system First will be explained the normal operating sequence, followed by the various possible sequences if there is la malfunction of the fuel burner, failure of electrical power service, or even if thecontrol system itselfshould breaky down, showing how this system is fail-safe kin Iunder many different circumstances. In normalropera'tion of the burner 10 and control sysoperation tem 111 the main power switch 2.0 remains closed atlallv times, and when .the temperature of the living space drops `tothe set level of-a room thermostat (not shown), then the room vthermostat is actuated so as -to call formore heat. This room thermostat serves to initiate opera-tion of a tluid circulator (not shown) for circulating a warm tiuid from the furnace to the living space which is to-be heated so as to supply heat to this space. This circulating fluid may be any suitable heat-transporting gas or liquid, for example,such as air, lwater, mixtures of water and an` anti-freeze agent, or liquid anti-freeze lagents,witht'ut-wa-i l ter. The most common circulating uids used are,.of course, 4air and water, in whichcases the Huid-circulatory f is a blower or a pump, but it is to be understood that the present invention is applicable to fuel burning domestic heating systems of all types, regardless of the type of uid which is used to distribute the heat from 'the'gfurnace to the space to be heated. `V v When the room thermostat Vcalls for heat, `then :the

uid circulator produces circulation of the heat-transporta ing uid, andthis fluid Lbecomes reduced in temperatureV as thev heat isabstracted therefrom.` The fluid-tempera-4 ture-sensing thermostat 22,. is normally open,fand it is responsiveV to the temperature conditionsV in the heating system. For example, in 'a warm air heating system Vthis Ythermostat 22 senses the temperature of the air being circulated,` and in a Warm wateri'circulating system. this Y thermostat .22 senses the temperature of thecirculated water. When the temperature of thisuid drops to the set level of the thermostat 22, then the contacts 52 'of The normally the thermostat 22 close to that the burner 10 is turned on, as will be explained further below.

Also, there lare heating systems wherein the domestic hot water supply is heated by the furnace, and in such systems there is a thermostat such as at 22 which is arranged to be responsive to the temperature of the water supply source. In such cases there may be two thermostats 22 in parallel, one for sensing the circulating fluid and one for sensing the hot water supply. When the temperature of either fluid drops below the set level of its thermostat 22, then the contacts S2 of the thermostat 2.2 are closed to turn on the burner 10.

`ing for heat by completing a circuit passing through theA time-delay switch 14 and the relay coil 46.

This circuit is traced from the `hot line'29 through the main switch 20, the fuse 31, lconnection 33, lline 34, remote reset switch 24, line 35, connection 37, now closed contacts 52, line terminal 32, supply line 36, connection 44, heater 43, Contact arm `42, normally closedcontacts 40,` relay winding 46, ground terminal 48, and lead 54 extending to the ground power line` 30. Consequently, the relay winding 46 is energized s-o as to close its contacts 49 and thus to energize the burner 10 to place it in operation. The circuit for energizing the burner l is traced from the supply line 36 through a lead 59 to the now-closed contacts 49 and through a connection 53 to the burner terminal 50 and thence to the burner 10, with the opposite side of the burner being connected through the wire 54 to the power line 30. In normal operation as being discussed here the Iburner 10 ignites, and combustion continues so `as to begin warming -up the heat sensor i12. Thus, the ame sensor contacts 38 become closed before the time-delay period of switch 14 has elapsed, and hence current liow is Vestablished through these contacts 38 and through connection 39 to the movable arm 42 and through the contacts 40 to the relay coil 46 so as to maintain the relay contacts 49 closed. The heating element 43 of the time-delay switch 14 is now by-passed by the contacts 38, and hence the heater 43 stops heating, and `so the switch 14 does not trip. The burner 10 continues to function until the thermostat 22 is satised, at which time the thermostat contacts 52 open, causing the relay contacts 49 to open `so as to shut oli the burner 110.

In this example the burner 10 includes a fuel source -and ignition circuit, which become actuated so as to initiate and then continue combustion as long as the relay contacts 49 are closed.

In one possible type of malfunction the burner 10 may fail to ignite. During this sequence the thermostat contacts 52 close, calling for heat as discussed above, by completing a circuit through the time-delay switch 14 and through therelay coil 46 so as to close the relay contacts .49. Since the burner fails to ignite, the heat sensor i12 remains cool and its contacts 38 remain open. After the time-delay period has elapsed, the contacts 41 'become closed by the heating action of the element 43 so as to complete a circuit through the circuit means 51 to the warning buzzer 18, and the contacts 40 become opened so as to de-energize the relay Icoil 46, thus shutting off the energizing circuit to the burner 10.

The warning signal continues until the main power switch 20 is either opened or until a reset button S6 is pushed so as to open the reset-switch contacts 57. Either of these switches 20 or 24 interrupts the current flow so as to allow the heater 43 to cool, and hence the timedelay switch 14 returns to its initial position as shown. When the respective switch 20 or 24 -is again closed, then lthe burner 10 is again energized, because the thermostat 22 is continuing to call for heat. If the burner now ignites properly and continues t-o burn then the sequence of operation is normal as discussed above. But if the burner fai-ls to ignite a second time, then the warning signal again occurs as before, and so -the user will make 6 a telephone call to the burner service organization.

The warning device 18 is shown as a buzzer, but it is to be understood that any suitable audible or visual warning device or combinations of them may be used. They may be connected for simultaneous operation, for ex- -ample being connected in parallel, and may include devices such as a light 28, an electric horn, bell and the like. Also, these warning devices 26 and 28 may be located remotely from the burner by making connections at the respective points x, x as indicated, and one or more of them may be used in parallel, such as an `audible device plus Va visual device.

In this example the reset switch 24 is shown as being included, but it may be omitted by making a jumper connection 58 directly Ibetween the connection points 33 and 37 in which case the main power switch 20 is used as the reset switch. This main power switch 20 may be located on an electrical service panel near the incoming electrical power service connections for the home. However, it is usually desirable to have the main power shut-oil switch 20 in the same room as the burner or in the vicinity of the burner for safety, and so that anyone who is servicing the burner can be sure that the switch remains ott. For these reasons it is advantageous to include a reset switch 24 in addition to the main switch 20, with this reset switch being in circuit in series with the fluid-temperature-sensing thermostat 22. In some installation the reset switch 24 is located in the living quarters adjacent to a room thermostat which is responsive to the temperature of the living quarters, and the `reset switch 24 may be incorporated as part of the room thermostat control. Advantageously, this reset `switch 24 may comprise an emergency shut-ofi switch which is now-existent in many homes at a convenient location remote from the burner, thus enabling this existing switch to reset the control system 11.

The above discussion reviewed (1) normal operation of the burner and (2) failure of the burner to ignite. A ,third possibili-ty is that the burner becomes extinguished after proper combustion has occurred for a while and during the time while the Huid-sensing thermostat 22 is still calling for heat. In this event the heat sensor 12 cools oli so as to open its contacts 38. Then, after the time-delay period has passed the switch 14 energizes the warning signal and deenergizes the relay 16 so as to shut oil the electrical circuit to the burner.

A fourth possible chain of events involves the failure of a component of the control system 11. Should the heater 43 burn out or should contacts 40 remain open or should relay coil 46 become open-circuited, then the burner 10 could not be initially energized, because the relay contacts 49 cannot become cl-osed. These contingencies all lead `to a fail-safe result. Should the heat sensor 12 fail to operate, then its contacts 38 remain open, and at the end of the time-delay period, the switch 14 shuts ol the burner and actuates the alarm, which is a fail-safe result.

Lastly, should the electrical power fail, then the control circuit 11 automatically resets itself in readiness to start the lburner as soon as the electrical power is restored. Cessation of the electrical power has the effect of opening the relay contacts 49 while allowing the heat sensor 12 and the time-delay switch 14 to return to or to remain in their initial ready positions as shown in FIGURE l. This is an automatic, safe, and convenient result.

Although domestic oil burners have been discussed, it will be appreciated that -the control system 11 may be adapted as a safeguard and convenience for use with other types of fuel burners and for commercial and industrial applications, involving burners.

In the control circuit of FIGURE l, it is to be understood that the warning device may be connected to the normally closed contacts 62 of the ,relay 16. It is noted that the warning device 18 is shown as being an integral part of the control system unit, which is surrounded by -the dotted line 64. This unit 64 may be included in a casing adapted to be connected in a suitable place on the furnace so that the thermostatic element 37 of the llame sensor responds to the heat of combustion, for example, the unit 64 is'mounted on the side ofthe burner stack duct with the sensing element 37 projecting into the stream of exhaust gases passing through the duct.

In thecontrol circuit 11 `of FIGURE 1y the contacts 38 of the stack-switch sensor 12 are in circuit'in shunt with the heater element 43. It is possible .to disconnect the lead 39 from the point A and to reconnect the lead 39 to the point B so that the contacts 38 are in shunt with both the heater 43 and the normally-closedtime-- delay contacts 40, as is shown :by the dotted line 39'.` `With this 39 connection arrangement ther contacts 38 are 'effectively in shunt with the heater 43 and so the B-con- 'nection 39will operate almost as well as theA-connecfV tion 39. The A-connection 39'ispreferred for the reason that it is more vreliably fail-safe than .the B-connectionV 39'. YWhen using the B-connection39, there is a remote possibility of an undesired coincidence, namely,Y that the stack switch contacts 38 might close themselves` just at the end of the time-delay period when the contacts 40 are about .to beopened. In thiskunlikely coincidence situation the stack switch`contacts 38 would remain closed, thus maintaining the burner in operation, even though the contacts 41 have now become closed so as to produce a warning signal. Thus, the homeowner might be induced to operate the reset switch, or to make a telephone call asking for service for the burner, even though the burner itself is actually continuing to funcf tion satisfactorily. This coincidence of closure and opening can Abe avoided by making the time-delay period assuredly longer than the closure period of ythe stack-switch contacts 38. However, the A-connection 39places the Y contacts 40 in series'with the contacts 38 and thus'closure of the stack-'switch contacts 38 willmaintainthe burner in operation only if the contacts 40 remain closed, thus avoiding any possibility for this coincidence to occur. Y

It is to be noted that either the A-connection 39 or the B-connection 39 places the contacts 38 effectively in shunt'with .the heater element 43, but the A-connection 39 is preferred for the reasons discussed immediately above. I

` The system 11A of FIGURE 2 is identical with the system of FIGURE 1, except that the warning `signal apparatus 18 is connected in series with a pair of normal- 1y closed contacts 62 which are operated by the magnetic relay 16. As long as the relay 16 is energized, then the contacts 62 are held open so that the warning apparatus 18 remains de-energized. One other difference between vthe system 11A and system 11 is that the circuit means 51 may have the warning device omitted therefrom..

Before describing the system of FIGURE 3 yin detail it is to be noted that there are two common .typesy of ignition `systems generally utilized in domestic oilV burners. One is termed constant ignition, wherein the ignition transformer continually produces a spark to ignite the oil during the whole of each time period that the burner is in operation. The second type of ignition system `is variously termed as interrupted or intermittent ignition.`

In .this second type the ignition circuit operates for a f short initial time 4period so as to initiate combustion.

After this initial time period `has, passed, the transformer of `the lignition circuit is turned off and the combustion in the burner continues by being'self-sustaining.

The control system 11B shown in 'FIGUREl 3 is Vgen` erally similar tothe system 11 of FIGURE 1 and simi-V lar to the system 11A of FIGURE 2, exceptthat a second magnetic relay 6'8 is included having la coil 69. connected in parallel with the heater 43. This relay. 68 includes a pair of contacts 70 which are in circuit connected bentween the'burner terminal 50 and another terminal 72,

which is designated as the terminal for connection to an ignition circuit 74 of the burner.

Whenever the heater 43` =is energized (which occurs during the initial phase of each normal burner starting'v operation) then the relay coil 691s also energized so as lto close the contacts 70, .thus supplying electricity to the ignition circuit 74.l When the heat sensor contacts 38 close upon detection of a rise in temperature, then the relay coil 69 is by-passed, yresulting in the openingpof:

contacts 70 to lproduce de-energization of the 4ignition circuit 74' and the burner continues self-sustaining combustion until the thermostat 22 has been satisfied. n

Should a flame-out occur duringV operation, the cooling ofther heat sensor- 12 causes its contacts 38'to-open, n' Vthereby energizing -both theheater 43V andrelay coil 69.1Y

The ignition circuit-74-becomes re-energizedand the ignition, spark continues duringthe time-delay period while lthe heater; 43 remains energized and while the con- -tacts 40 are still jclosed.` 'If the 'llame is re-establislied,"iV

during this period,.then the system k11A reverts .back Vto its normal operation kwith the burner continuing self-sustaining combustion until .the thermostat 22 has` been satised. However, if the flame isnot re-established, then the the time-delay switch closes its contacts 41`and opens `its contacts40 so as to provide a warning signal and to de-energize the burner terminal 50,'thus shutting ot the whole burner including a shut-olf of the ignition circuit 74.

It is is be noted that .the relay coil 69 and the heater 43 are shown in parallel, `but the circuit can also be made to operate with the relay coil, 69 vin seriesvwith the heaterV 43. The v'parallel' ,arrangementv is preferred` because it ravoids Yany balancing of the-seriesl circuitso VVas to assure proper currentvalues vthroughfthese.two.

components. Y In the parallel connection as Vshown the relay coil 69 is arranged yto have-a suciently'high electrical impedance relative Vto the heater 43 for assuring adequate current ow through the heater, thus providing fail-safe operation.

The sensor 37 which responds to energy resulting from combustionmay ybe a photoconductive material which provides a veryhigh resistance in the absence of light energy. This high resistance is equivalent to the presence of open contacts 38.I When light energy from the combustion tlame is present, then this photoconductive material provides a Very low resistance, which is equivalent to closure of the contacts 38 so as to by-pass the timedelay element 43. Thus, it is to be understood .that the purpose of .the combustion energy sensor `12 is to by-` pass current around the `time-delay element 43 when combustion is present, and so the use of photoconductive material ,is equivalent to heat sensing means 37 plus C011-,l tacts 38. In installations wherein it is desired to use a minimum time-delay periodvof the order of lseconds4 or so, for example, in larger furnaces wherein the fuel comsumption rate is above 5 4gallons per hour, then it is an advantageto use such photoconductive material as l .the combustion energy sensor 12, .because it provides a more rapid response to the presence of proper combustion than does -a thermostat probe in the exhaust duct.

into the burner.

larger burner installations.

It is noted that the circuit means 51 :may include a resistor 75 in parallel with the warning device 18. This resistor 75 serves to maintain the time-delay switch 14 electrically locked in the burner-deenergized condition by maintaining current flow through the time-delay means 43 even though the warning device 18 may become burned out. Thus, it is seen that the circuit means S1 provides the function of electrically locking the system in the condition wherein the burner remains de-energized, until current flow through the circuit including elements 43and 51 is interrupted.

From the foregoing it will be understood that the oil burner stack switch control systems described herein as illustrative embodiments of the present invention are well suited to provide the advantages set forth and that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense and that in certain instances some of the features of the invention may be used without a corresponding use of other features or may be modified into equivalent elements, Iall Without departing from the scope of the invention as defined by the following claims.

What is claimed is:

.1. A safety oil burner control for controlling the operation of an oil bu-rner system and for de-energizing the burner in the event of malfunction of the system, said control comprising at least three terminals, one of these terminals being designated the burner terminal and being adapted to be connected to the oil burner, another of these terminals being designated the thermostat terminal and being adaptedto be connected through a thermostat to one side of a source of electrical power, another of these terminals being designated a ground terminal and being adapted to be connected to the opposite side of the electrical source from the thermostat terminal; an electrical relay having normally open contacts and a coil for closing said contacts in response to .a flow of electrical current through said coil, said relay contacts being in circuit between said thermostat terminal and said burner terminal for interrupting the supply of electrical power to said burner terminal when said relay contacts are open; a time-delay thermally-actuated switch having normally open and normally closed contacts and a resistance heating element for closing the normally open contacts and for opening the normally closed contacts after an appropriate time delay, said heating element, said normally-closed contacts of the time-delay switch and said relay coil being -in a i'lrst circuit in series relationship between said thermostat terminal and said ground terminal; combustion energy responsive means being eiectively shunted across said heating element for luy-passing electrical current around said heating element when said combustion-energy responsive means is actuated by energy resulting from combustion; and a warning device, said heating element, said normally-open contacts of the time-delay :switch and said warning device being in a second circuit in series relationship between said thermostat terminal `and said ground terminal, said second circuit conducting electrical current actuating said warning device and keeping said heating element heated for maintaining said normally-open contacts in their closed position after said normally-open contacts have closed.

2. A safety oil-burner stack switch control system comprising a burner control terminal adapted to be connected to an oil burner; first `and second power connections adapted to be connected to opposite sides of a source of electrical power; an electrical relay having normally open contacts and a coil for closing said contacts in response to a flow of electrical current through said coil, said relay contacts being in circuit with said burner control terminal for interrupting the supply of electrical power to said burner terminal when said relay coil is de-energized; a huid-temperature-sensing thermostat having normally open contacts and means for closing said contacts upon a drop in temperature of the fluid to a set limit; a reset switch having normally closed contacts and manually operable control means for opening said -reset contacts; a stack switch having normally open contacts and heat-responsive means for closing said stack-switch contacts in response to heat of combustion in said burner, said stack-switch contacts and said relay coil and said thermostat contacts and sa-id remote reset switch contacts being in circuit in series between said rst and second power connections; a time-delay thermally-actuated switch having normally open and normally closed contacts and a resistance heating element for closing the normally open contacts and for opening the normally closed contacts after an appropriate time delay, -said heating element, said normally-closed contacts, said relay coil, said thermostat contacts and said remote reset contacts being in circuit in series between said first and second power connections; circuit means connecting said stack-switch contacts effectively in shunt relationship with said heating element for by-passing current around said heating element when said stackswitch contacts are closed; and electrically conducting circuit means connected in said system in series with said heating element for energization of said heating element when said normally-open contacts of said timedelay switch are closed maintaining said heating element heated for maintaining said normally-open contacts closed.

3. A safety oil-burner stack switch control system comprising a burner control terminal adapted to be connected to an electrical circuit of an oil burner for controlling the burner and for de-energizing the burner in the event of malfunction in the system, an electrical relay having normally open contacts and a Winding for closing said contacts in response to a ow of electrical current through said relay winding, said contacts being in circuit in serial relationship with said control termin-al for interrupting the supply of electrical power. to the burner terminal whenever said contacts are open, a stack switch having normally open contacts and heat-responsive means for closing said stack-switch contacts in response to heat of combustion in said burner, said stack-switch contacts and said relay winding being in circuit in serial relationship, a time-delay thermally-actuated switch having normally open contacts and also having normally closed contacts and a resistance heating element for closing the normally open contacts and for opening the normally closed contacts after an appropriate delay time, iirst circuit means connecting said heating element and said normally closed contacts in serial relationship with said relay winding with said stack-switch contacts in circuit in shunt -relationship with said heating element, and second circuit means includ-ing a warning device connecting said resistance element and said normally open contacts in circuit relationship with said warning device, said second circuit means maintaining said resistance element heated suiciently upon closure of said normally-open contacts to maintain said normally-open contacts closed.

4. A safety oil-burner stack-switch control system controlling the operation of an oil burner and for de-energizing the burner in the event of malfunction; said control system comprising at least three connections, one of these connections being the burner connection and being adapted to be connected to the oil burner, another of these connections being the line connection and being adapted to be connected to the hot side of 'a source of electrical power, another of these connections being a ground connection and being adapted to be connected to the opposite side of the electrical source from the line connection; a remotely located switch having contacts and switch means for opening said contacts; -a fluid-temperature sensing thermostat having normally open contacts adapted to be closed by a drop in temperature of the uid to a set value; circuit means for connecting said remotely located switch and said thermostat contacts in serial relationship between the hot line and said line connection; an electrical relay having normally open contacts and a coil for closing said contacts in response to a flow of electrical current through said relay coil, said relay contacts being in switch contacts become closed. Y

circuit between said line connection and said `burner connection for interrupting the supply of electrical power to said burner connection when said relay coil is de-energized; a time-delay thermally-actuated switch having normally closed contacts and electrically actuated opening means for opening the normally-closedcontacts after an appropriate -time delay, said opening means, said normally-closed contacts of the time-delay switch and said relay coil bein-g in circuit in serial relationship between said line connection and said lground connection; a stack switch having normally open contacts and heat-responsive means for closing said stack-switch contacts 'm response to heat of combustion in said burner, said stack-switch contacts beingl eiectively shuntedacross said opening means for by-passing electrical current around said'openf ing means when said heat-responsive means of the stack 'switchis warmed from, the heat of combustion, and cir# cuit means maintaining c urrentilowV through said'opening means maintaining said normally-closed contacts openv stack v when the time-delay period elapses'before said y5. Asafety oil burner control system'for controlling the operationof an oil burner and for deaene'rgizing they burner in the event of malfunction; said control system comprising at least three connection-s, one of these convnections being the burner connection and being adapted to be connected to the oil burner, another of these connections being the line connection and being adapted to be connected to the .hot side of a source of electrical power, another of these connections being a ground connection and being adapted to be connected to the opposite side of the electrical source from the line connection; a remotely located switch having contacts and switch means for opening n said contacts; a uid-temperature-sensing thermostat having normally opencontacts adapted to be closed lby a drop in temperature of the uid to a set value;

circuit means for connecting said remotely located switch contacts and said thermostat contacts in serial relationship relay having normally open contacts and a coil for closing said contacts kin response 'to a flow of electrical current through said relay coil, said relay contacts being in cirl Vcuit between said line connection and said burner connection for interrupting the supply of electrical power to said burner connection when said relay coil is de-enerygized; a time-delay switch having normally closed contacts and normally open contacts and delay means for opening the normally-closed contacts and for closing the normally-open contacts afterr an appropriate time delay, and for maintaining said normally-opencontacts closed solely by the ow of electrical current through said delay means, said delay means, said normally-closed contacts of meansy is actuated by energy resulting from combustion;

and circuit means connected in serial relationship with said normally-open contacts of said time-delay switch and said delay means between said lineconnection and said ground connection for electrically locking said time-delay switch with said normally-open contacts closed by main-`Y taining current ilow through said delay means.

6. A safety oil-burner stack switch control system comprising iirst, second, and third terminals, saidrst terminalV being adapted to be connected to an oil burner, said second and third terminals being adapted to be connected to opposite sides of a source of electrical power, a warn# ing device, a thermostat switch, an electrical relay having between the hot line and said line connection; an electrical v tact-s closed.

l2 normally open contacts and a coil for closing said contacts in response to a ow of electrical current through said coil, said contacts being in circuit in series with said iirst terminal for interrupting the supply of electrical power to said lirst terminal when said contacts are open, a stack switch having normally open contacts and heat-responsive means for closingV said stack-switch contacts .in

response to heat of` combustion in said burner, said stackswitch contacts, said relay coil, and said thermostat switch being in circuit in series between said seco'nd and third terminals, a time-delay thermally-actuated switch having normally open and normally closed contacts and a resistance heating element for lclosing the normally open contacts and for opening the normally closedY contacts Yafter an appropriate time delay, said resistance element and said normallyclosedcontacts being in seriesand be-f ing shunted across'said stack-switch contacts, and circuit means connecting said warning device, said'resistance ele- .l ment and said normally open contacts in series shunted across Vboth said stack-switchcontacts and said relay coil, said circuit means maintaining saidvresistance .element Vheatedrsulciently to maintain said .normally-open lcon- 7. A safety oil-burner stack' switch control system comprising a burner control terminal adapted to be connected to an oil burner; iirst and second power `connections adapted to be connected to opposite sides of a source of electrical power; an electrical relay having normally open contacts andra coil for closing said contacts in response to a ow of electrical current through said relay coil; a

thermostat having normally uid-temperature-sensing open contacts and means for closing said contacts upon a rrise in temperature of the uid to a set limit; a remoteV vreset switch having contactsvand, manually operable control means :for opening Vsaid reset contactsyiirst` circuit 1 means connecting said remote reset contacts, said thermo-k stat contacts, and said relay contacts in serialrelationship between said rst power connection andisaid'burner control terminal for de-energizing the burner when `any of the aforesaid contacts are open; a time-delay switch having normally openV4 and normally close contacts and delay means for closing the normally open `contactsand for opening the normally Yclosed contacts 'aftersanap-V propriate time delay; second circuit means connecting said remote reset contacts, said thermostatcontacts, said delay means, said normally-closed contacts of the timedelay switch, and said relay coil in serial relationship be:

tween said irst and second power connections; ka stack switch having normally open contactsand heat-responsive means for closing said stack-switch contacts in response to' heat of combustion in said burner; third circuit'means connecting said stack-switch contacts electively in shunt relationship with said delay means for by-passing current around said delay means when said stack-switch contacts are closed; a warning device; and fourth circuit means connecting said warningrdevice between said normallyopen contacts of the time-delay switch and saidV second power connection, said fourth circuit means actuating said delay means to maintain said normally-open contac closed.

- 8. A safety oil-burner stack switch control system comprising a burner control terminal adapted to be connected to an oil burner; rst and second power connectionsY adapted to be connected to opposite sides of a source of electrical power; an electrical relay having normally open contacts and also normally closed contacts and a coil for closingfsaid normally-open contacts and'foropening said n normally-closed contacts in response to a ilowof electrical current` through said relay coil; a Huid-sensing. thermostat having normally open conta'cts'andmeansl for closing said contacts upon a rise in temperature of the lluid to a set limit; a remote reset switch having `contacts and manually operable control means for opening said reset contacts; first circuit means connecting said remote reset contacts,said thermostat contacts, and said normally-open relay contacts in serial relationship between said first power connection and said burner control terminal for de-energizing the burn-er when any of the aforesaid contacts are open; a time-delay switch having normally open and normally closed contacts and delay means for closing the normally open contacts aud for opening the normally closed contacts after an yappropriate time delay; second circuit means connecting said remote reset contacts, said thermostat contacts, said delay means, said normally-closed contacts of the time-delay switch, and said relay coil in serial relationship between said first and second power connections; a stack switch having normally open contacts and heat-responsive means for cl-osing said stack-switch contacts in response to heat of combustion in said burner; third circuit means connecting said stack-switch contacts effectively in shunt relationship with said delay means forby-pa-ssing current around said delay means when said stack-switch contacts are closed; a warning device; fourth circuit means connecting said warning device between said normally-open contacts of` the time-delay switch and said second power connection, said fourth circuit means conducting suicient current maintaining said delay means actuated to maintain the normally-open contacts closed; and a terminal connected to said normally-closed relay contacts adapted to be connected to a remote warning device.

9. A safety oil burner stack switch control system cornprising a burner control terminal adapted to be connected to an electrical circuit of an oil burner for contro-lling the burner and for de-energizing the burner in the event of malfunction in the system, an electrical relay having normally open contacts and a winding for closing said contacts in response to a flow of electrical current through said relay winding, said contacts being in circuit in serial relationship with said control terminal for interrupting a supply of electrical power to the burner terminal whenever said contacts are open, a stack switch having normally open contacts and -heat-responsive means for closing said stack-switch contacts in response to heat of combustion in said burner, said stack-switch contacts and said relay winding being in circuit in serial relationship, a time-delay thermally-actuated switch having normally open contacts and also having normally closed contacts and a resistance heating element for closing the normally open contacts and for opening the normally closed contacts after an appropriate delay time, first circuit means connecting said heating element and said normally closed contacts in serial relationship with said relay winding, with said stack-switch contacts in circuit in shunt relationship with said heating element, and second circuit means for connecting said resistance heating element and said normally open contacts in serial relationship with a supply of electrical power for maintaining said heating element heated suiciently to maintain said normallyopen contacts clos-ed for electrically locking said timedelay lswitch with said normally-open contacts closed, thereby to maintain said burner de-energized.

10. A safety oil-burner control for electrically de-energizing an oil burner in the event of malfunction of the burner and for electrically locking the burner in its deenergized condition until the system is conveniently reset by interrupting the flow of electricity in the system, said safety control including relay means having a set of normally open contacts and a terminal connected thereto forV electrically energizing the burner in response to energization of said relay means and for de-enengizing the burner in response t-o de-energization of said relay means, timedelay switch means having first and second conditions of operation and being connected to said relay means for energizing said relay means durin-g a time-delay period while said time-delay switch means is in said first condition and electrical resistance heating means thereafter switching said time-delay switch means into its second condition,

circuit means connected to saidV time-delay switch means for maintaining said resistance heating means heated sufiiciently .to maintain said time-delay switch means in said second condition, combustion energy sensing means connected in circuit with said relay means for effectively shunting said time-delay switch means in response tothe presence of combustion in said burner lfor maintaining energization of said relay means, and a second terminal connected in circuit with said time-delay switch means for being connected to rem-cte reset control means `for interrupting the ow of electricity in said resistance heating means thereby to reset said time-delay switch means in the rst condition in readiness for attempting to initiate proper operation' of the burner.

11. A safety oil-burner control for controlling the ignition circuit of an oil burner and for electrically de-energizing an oil burner in the event of malfunction of the lburner and yfor electrically locking the burner in its deenergized condition until the system is conveniently reset by interrupting the flow of electricity in the system, said safety control including first relay means having a terminal connected thereto for ibeing connected to an oil burner for electrically energizing the burner in response to energization of said first relay means and for de-energizing the burner in response to de-energization of said first relay means, time-delay switch means having first and second conditions of operation and electricalrresistance heating means, said time-delay switch means being connected to said relay means for energizing said rst relay means during a time delay period while said time-delay switch means is in said first condition and said heating means thereafter switching said time-delay switch means into its second condition, circuit means connected to said time-delay switch means for electrically heating said heating means sutiiciently to maintain said timedelay switch means in said second condition, combustion energy sensing means connected in circuit with said rst relay means for effectively shunting said time-delay switch means in response to the presence of combustion in said burner for maintaining energization of said rst -relay means, and, second relay means connected to said timedelay switch means, said second relay means having a second terminal connected thereto for being connected to the ignition circuit of the burner for energizing the -ignition circuit when said time-delay switch means are energized in the first condition, and a third terminal in circuit with said time-delay switch means for being connected to remote reset control means for interrupting the flow of electricity in said time-delay switch means, thereby to reset said time-delay switch means in the first condition in readiness for attempting to initiate proper operation of the burner.

12. A safety oil burner control comprising a burner control terminal adapted to be connected to an electrical circuit of an oil burner for controlling the burner and for de-energizing the burne-r in the event of malfunction in the system, a warning terminal adapted to be connected to a warning device for providing a warning signal when said warning terminal is energized, an electrical relay having normally open contacts and a winding for closing said contacts in response to a ow of electrical current through said relay winding, said contacts being in circuit in serial relationship with said control terminal for interrupting a supply of electrical power to said control terminal whenever said contacts are open, said relay also having normally closed contacts in circuit in serial relationship with said warning terminal for closing an electrical circuit to said warning terminal when said relay winding is deenergized, a combustion sensor having normally open circuit condition and heat-responsive means for closing said open circuit condition -in response to combustion in said burner, saidv combustion sensor and said relay winding -being in circuit in serial relationship, a time-delay thermally-actuated switch having normally open contacts and also having normally closed contacts and a resistance heating element for closing the normally open contacts and `for opening the normally closed contacts after an appropriate delay time, first circuit means connecting said heating element and said normally closedk contacts in serial relationship with said relay winding and connecting said combustion sensor in circuit yin shunt relationship with said heating element, and second circuit means for connecting said resistance element and said normally open contacts in serial relationship with a supply of electrical power for electrically heating said resistance element sufcicntly to maintain said time-delay switch with said normally-open contacts closed, the-reby to maintain said burner de-energized. f

13. A safety oil-burner control yfor electrically deenergizing an oil burner and for electrically locking the *burner in its de-energized condition comprising relay meansI having a relay `winding for de-energizing `the burner, thermal time-delay switch means havinga resistance heater,a normally closed switch and aV heat-responsive elementopening said switch after a time-delay periodV in response -to the heat from said heater, said relay wind-'- open-circuit in the absence of combustion and becoming closed-circuit when combustion is present, said sensing means effectively by-passing said heater when combustion is present, and circuit means maintaining currentiow through said Yheater Whentsaid normally `closed contacts are opened for solely electrically locking said normally closed switch open to de-energize the burner, by all of Whichfthe burner can be remotely resetl into energized 4condition by interrupting said circuit means to stop `current flow through said heater.

References Cited by the Examiner UNITED STATES PATENTS 2,384,372 9/1945 Eaton 158;.-28` 2,842,192 7/1958 Palm 15s-28 3,144,898 8/1964 Queever Y 158- 28 3,196,923; 7/1965 se1inderf r r 158-28` Y Y FOREIGNV PATENTS@ 197,946 Y11/1957 Austria.'-

173,006 2/1935 Switzerland. t

JAMES W. WESTHAVER, Primary Examiner. 

1. A SAFETY OIL BURNER CONTROL FOR CONTROLLING THE OPERATION OF AN OIL BURNER SYSTEM AND FOR DE-ENERGIZING THE BURNER IN THE EVENT OF MALFUNCTION OF THE SYSTEM, SAID CONTROL COMPRISING AT LEAST THREE TERMINALS, ONE OF THESE TERMINALS BEING DESIGNATED THE BURNER TERMIANL AND BEING ADAPTED TO BE CONNECTED TO THE OIL BURNER, ANOTHER OF THESE TERMINALS BEING DESIGNATED THE THERMOSTAT TERMINAL AND BEING ADAPTED TO BE CONNECTED THROUGH A THERMOSTAT TO ONE SIDE OF A SOURCE OF ELECTRICAL POWER, ANOTHER OF THESE TERMINALS BEING DESIGNATED A GROUDN TERMINAL AND BEING ADAPTED TO BE CONNECTED TO THE OPPOSITE SIDE OF THE ELECTRICAL SOURCE FROM THE THERMOSTAT TERMINAL; AN ELECTRICAL RELAY HAVING NORMALLY OPEN CONTACTS AND A COIL FOR CLOSING SAID CONTACTS IN RESPONSE TO A FLOW OF ELECTRICAL CURRENT THROUGH SAID COIL, SAID RELAY CONTACTS BEING IN CIRCUIT BETWEEN SAID THERMOSTAT TERMINAL AND SAID BURNER TERMINAL FOR INTERRUPTING THE SUPPLY OF ELECTRICAL POWER TO SAID BURNER TERMINAL WHEN SAID RELAY CONTACTS ARE OPEN; A TIME-DELAY THERMALLY-ACTUATED SWITCH HAVING NORMALLY OPEN AND NORMALLY CLOSED CONTACTS AND A RESISTANCE HEATING ELEMENT FOR CLOSING THE NORMALLY OPEN CONTACTS AND FOR OPENING THE NORMALLY CLOSED CONTACTS AFTER AN APPROPRIATE TIME DELAY, SAID HEATING ELEMENT, SAID NORMALL-CLOSED CONTACTS OF THE TIME-DELAY SWITCH AND SAID RELAY COIL BEING IN A FIRST CIRCUIT IN SERIES RELATIONSHIP BETWEEN SAID THERMOSTAT TERMINAL AND SAID GROUND TERMINAL; COMBUSTION ENERGY RESPONSIVE MEANS BEING EFFECTIVELY SHUNTED ACROSS SAID HEATING ELEMENT FOR BY-PASSING ELECTRICAL CURRENT AROUND SAID HEATING ELEMENT WHEN SAID COMBUSTION-ENERGY RESPONSIVE MEANS IS ACTUATED BY ENERGY RESULTING FROM COMBUSTION; AND A WARNING DEVICE, SAID HEATING ELEMENT, SAID NORMALLY-OPEN CONTACTS OF THE TIME-DELAY SWITCH AND SAID WARNING DEVICE BEING IN A SECOND CIRCUIT IN SERIES RELATIONSHIP BETWEEN SAID THERMOSTAT TERMINAL AND SAID GROUND TERMINAL, SAID SECOND CIRCUIT CONDUCTING ELECTRICAL CURRENT ACTUATING SAID WARNING DEVICE AND KEEPING SAID HEATING ELEMENT HEATED FOR MAINTAINING SAID NORMALLY-OPEN CONTACTS IN THEIR CLOSED POSITION AFTER SAID NORMALLY-OPEN CONTACTS HAVE CLOSED. 